The invention relates generally to mobile assets, and more specifically to a fuel optimizing system for engines using more than one fuel.
Generally, mobile assets having engines, for example, compression-ignition engines, operate by directly injecting a fuel (e.g., diesel fuel) into compressed air in one or more piston-cylinder assemblies, such that the heat of the compressed air ignites the fuel-air mixture. The direct fuel injection atomizes the fuel into droplets, which evaporate and mix with the compressed air in the combustion chambers of the piston-cylinder assemblies. The fuel-air ratio affects engine performance, efficiency, exhaust pollutants, and other engine characteristics. Exhaust emissions generally include pollutants such as carbon oxides (e.g., carbon monoxide), nitrogen oxides (NOx), sulfur oxides (SOx), and particulate matter (PM). The amount and relative proportion of these pollutants varies according to the fuel-air mixture, compression ratio, injection timing, environmental conditions (e.g., atmospheric pressure, temperature), and so forth.
A dual-fuel engine is an alternative internal combustion engine designed to run on more than one fuel, for example, natural gas and diesel, each stored in separate vessels. Such engines are capable of burning a mixture of the resulting blend of fuels in the combustion chamber and the fuel injection or spark timing may be adjusted according to the blend of fuels in the combustion chamber. For dual fuel operation where one of the fuel is premixed with air, a reduction in nitrogen oxide (NOx) and particulate matter (PM) emissions is enabled by combusting a relatively larger fraction of the premixed fuel.
Relative costs and availability of different fuels are constantly in flux. Proportions of different fuels may also have an effect on the exhaust pollutants from the engine.
There is a need for an improved system and method for engines operating on more than one fuel so as to optimize fuel usage while meeting emission standards.